The protein glass transition as measured by dielectric spectroscopy and differential scanning calorimetry

The glass transition and its related dynamics of myroglobin in water and in a water-glycerol mixture have been investigated by dielectric spectroscopy and differential scanning calorimetry (DSC). For all samples, the DSC measurements display a glass transition that extends over a large temperature range. Both the temperature of the transition and its broadness decrease rapidly with increasing amount of solvent in the system. The dielectric measurements show several dynamical processes, due to both protein and solvent relaxations, and in the case of pure water as solvent the main protein process (which most likely is due to conformational changes of the protein structure) exhibits a dynamic glass transition (i.e. reaches a relaxation time of 100 s) at about the same temperature as the calorimetric glass transition temperature Tg is found. This glass transition is most likely caused by the dynamic crossover and the associated vanishing of the alpha-relaxation of the main water relaxation, although it does not contribute to the calorimetric Tg. This is in contrast to myoglobin in water-glycerol, where the main solvent relaxation makes the strongest contribution to the calorimetric glass transition. For all samples it is clear that several proteins processes are involved in the calorimetric glass transition and the broadness of the transition depends on how much these different relaxations are separated in time

The slow dielectric Debye relaxation of monoalcohols in confined geometries

Broadband dielectric relaxation measurements have been performed on monoalcohols confined in the quasi-two-dimensional space between clay platelets and the quasi-one-dimensional pores of approximately 10 angstrom diameter in a molecular sieve. Interestingly, the results show that the slow Debye-like process is present even in these severe confinements, proving that structural models that are based on two-dimensional or three-dimensional cluster formations as the structural origin of the Debye-like process can be excluded. Rather, the insensitivity of its time-scale to confinements suggests that it is of local character and in some way related to the lifetime or breaking and reformation of hydrogen bonds. (C) 2011 American Institute of Physics. [doi:10.1063/1.3563630

Role of Solvent for the Dynamics and the Glass Transition of Proteins

For the first time, a systematic investigation of the glass transition and its related dynamics of myoglobin in water-glycerol solvent mixtures of different water contents is presented. By a combination of broadband dielectric spectroscopy and differential scanning calorimetry (DSC), we have studied the relation between the protein and solvent dynamics with the aim to better understand the calorimetric glass transition, T-g, of proteins and the role of solvent for protein dynamics. The results show that both the viscosity related alpha-relaxation in the solvent as well as several different protein relaxations are involved in the calorimetric glass transition, and that the broadness (Delta T-g) of the transition depends strongly on the total amount of solvent. The main reason for this seems to be that the protein relaxation processes become more separated in time with decreasing solvent level. The results are compared to that of hydrated myoglobin where the hydration water does not give any direct contribution to the calorimetric T-g. However, the large-scale a-like relaxation in the hydration water is still responsible for the protein dynamics that freeze-in at T-g. Finally, the dielectric data show clearly that the protein relaxation processes exhibit similar temperature dependences as the alpha-relaxation in the solvent, as suggested for solvent-slaved protein motions

Slow Debye-type peak observed in the dielectric response of polyalcohols

Dielectric relaxation spectroscopy of glass forming liquids normally exhibits a relaxation scenario that seems to be surprisingly general. However, the relaxation dynamics is more complicated for hydrogen bonded liquids. For instance, the dielectric response of monoalcohols is dominated by a mysterious Debye-like process at lower frequencies than the structural alpha-relaxation that is normally dominating the spectra of glass formers. For polyalcohols this process has been thought to be absent or possibly obscured by a strong contribution from conductivity and polarization effects at low frequencies. We here show that the Debye-like process, although much less prominent, is also present in the response of polyalcohols. It can be observed in the derivative of the real part of the susceptibility or directly in the imaginary part if the conductivity contribution is reduced by covering the upper electrode with a thin Teflon layer. We report on results from broadband dielectric spectroscopy studies of several polyalcohols: glycerol, xylitol, and sorbitol. The findings are discussed in relation to other experimental observations of ultraslow (i.e., slower than the viscosity related alpha-relaxation) dynamics in glass formers

Calorimetric and relaxation properties of xylitol-water mixtures

We present the first broadband dielectric spectroscopy (BDS) and differential scanning calorimetry study of supercooled xylitol-water mixtures in the whole concentration range and in wide frequency (10(-2)-10(6) Hz) and temperature (120-365 K) ranges. The calorimetric glass transition, T-g, decreases from 247 K for pure xylitol to about 181 K at a water concentration of approximately 37 wt. %. At water concentrations in the range 29-35 wt. % a plentiful calorimetric behaviour is observed. In addition to the glass transition, almost simultaneous crystallization and melting events occurring around 230-240 K. At higher water concentrations ice is formed during cooling and the glass transition temperature increases to a steady value of about 200 K for all higher water concentrations. This Tg corresponds to an unfrozen xylitol-water solution containing 20 wt. % water. In addition to the true glass transition we also observed a glass transition-like feature at 220 K for all the ice containing samples. However, this feature ismore likely due to ice dissolution [A. Inaba and O. Andersson, Thermochim. Acta, 461, 44 (2007)]. In the case of the BDS measurements the presence of water clearly has an effect on both the cooperative a-relaxation and the secondary beta-relaxation. The a-relaxation shows a non-Arrhenius temperature dependence and becomes faster with increasing concentration of water. The fragility of the solutions, determined by the temperature dependence of the a-relaxation close to the dynamic glass transition, decreases with increasing water content up to about 26 wt. % water, where ice starts to form. This decrease in fragility with increasing water content is most likely caused by the increasing density of hydrogen bonds, forming a network-like structure in the deeply supercooled regime. The intensity of the secondary beta-relaxation of xylitol decreases noticeably already at a water content of 2 wt. %, and at a water content above 5 wt. % it has been replaced by a considerably stronger water (w) relaxation at about the same frequency. However, the similarities in time scale and activation energy between the w-relaxation and the beta-relaxation of xylitol at water contents below 13 wt. % suggest that the w-relaxation is governed, in some way, by the beta-relaxation of xylitol, since clusters of water molecules are rare at these water concentrations. At higher water concentrations the intensity and relaxation rate of the w-relaxation increase rapidly with increasing water content (up to the concentration where ice starts to form), most likely due to a rapid increase of small water clusters where an increasing number of water molecules interacting with other water molecules

Strategy for visualisation of the activity of phase change materials by transient plane source technique

Through a combination of theoretical and experimental research, this paper aims at evaluating the suitability of a transient plane heat source (TPS) method for the visualisation of the activity of phase change materials (PCMs). The TPS method provides measurements of thermal conductivity and thermal diffusivity of a material in a transient course. It has previously been tested on various building materials but not on PCMs. In this study TPS was tested in a laboratory environment on two inorganic PCMs (salt-hydrates), with melting temperatures 21 oC and 24 oC respectively. Based on the experimental trials, the technique has shown to be a valuable technique for the identification of the activity of phase change material

Cause of the fragile-to-strong transition observed in water confined in C-S-H gel

In this study, the rotational dynamics of hydration water confined in calcium-silicate-hydrate (C-S-H) gel with a water content of 22 wt.% was studied by broadband dielectric spectroscopy in broad temperature (110-300 K) and frequency (10(-1)-10(8) Hz) ranges. The C-S-H gel was used as a 3D confining system for investigating the possible existence of a fragile-to-strong transition for water around 220 K. Such transition was observed at 220 K in a previous study [Y. Zhang, M. Lagi, F. Ridi, E. Fratini, P. Baglioni, E. Mamontov and S. H. Chen, J. Phys.: Condens. Matter 20, 502101 (2008)] on a similar system, and it was there associated with a hidden critical point of bulk water. However, based on the experimental results presented here, there is no sign of a fragile-to-strong transition for water confined in C-S-H gel. Instead, the fragile-to-strong transition can be explained by a merging of two different relaxation processes at about 220 K. (C) 2013 AIP Publishing LLC

Skriftspråksutveckling med grammatiska metaforer. En systemisk-funktionell analys av gymnasieelevers utredande texter.

Under skolgången ställs det allt högre krav på att vi ska kunna uttrycka oss med språkbruk som är anpassat till vetenskaplighet. I gymnasieskolan, framförallt i studieförberedande program, tar det sig uttryck i alltmer akademiskt inriktade skriftliga uppgifter. Grammatiska metaforer är ett begrepp inom systemisk-funktionell grammatik som innebär att betydelser som naturligt uttrycks med en ordklass som verb eller adjektiv, istället uttrycks med ett substantiv. Denna nominalisering gör det möjligt att komprimera betydelser, att klassificera och att relatera olika fenomen till varandra på ett mer effektivt sätt, vilket är nödvändigt för vetenskapliga uttryck. Syftet med uppsatsen har varit att se i vilken utsträckning förmågan att använda grammatiska metaforer utvecklas under gymnasiet. Materialet har utgjorts av texter skrivna av 40 elever på gymnasiet vid två tillfällen. En del av eleverna deltog i utbildning med undervisning på engelska, andra deltog i normal undervisning. Resultatet visar entydigt att eleverna ökar användningen av grammatiska metaforer från skrivningen av den första uppgiften under termin 1 på gymnasiet till författandet av den andra uppgiften under termin 4. Det gäller materialet som helhet såväl som de olika grupperna och de enskilda eleverna. Med de grammatiska metaforerna kunde texterna göras mer abstrakta, tätare, och mer generaliserande. Ofta följer utvecklingen av hanteringen av grammatiska metaforer utvecklingen av kompetensen att konstruera dem. Det är dock inte givet utan grammatiska metaforer tillsammans med dess olika funktioner behöver lyftas fram explicit i undervisning för att ge alla möjlighet att utveckla förmågan att hantera grammatiska metaforer och de språkliga möjligheter som de för med sig.Interdisciplinärt examensarbete inom lärarutbildningen, LSV410 15hp Ämne: Svenska Termin: H15 Handledare: Per Holmber

Att bedöma andningsfrekvens-en del i en säker vård.

Att observera och bedöma patientens vitalparametrar inklusive andningsfrekvens ger en överblick av patientens tillstånd. Sjuksköterskan ansvarar för att bedöma och följa upp patientens tillstånd och agera vid eventuell försämring. En avvikande andningsfrekvens är ofta det tidigaste tecknet på en förändring i patientens tillstånd och kan vara ett tecken på att patienten försämras. Tidigare forskning visar att andningsfrekvens är den vitalparameter som inte alltid mäts och orsakerna till detta har varit bland annat bristande kommunikation, bristande utbildning i metoder för observation och hög arbetsbelastning. Syfte: Syftet med denna studie var att belysa hur sjuksköterskan observerar och bedömer andningsfrekvens hos patienter på en onkologisk vårdavdelning samt vilka faktorer som påverkar bedömningen. Metod: För att besvara vårt syfte valdes kvalitativ metod med induktiv ansats. Studien genomfördes med semistrukturerade intervjuer där sex sjuksköterskor på en onkologisk vårdavdelning intervjuades. Resultat: Analysen av insamlat material resulterade i tre kategorier med åtta underkategorier. Metoder för observation, specifika tecken i bedömningen och bedömning i ett helhetsperspektiv beskrivs i kategorin flerdimensionell bedömning. Diagnos, hälsotillstånd under vårdtiden och patientens medverkan beskrivs i kategorin patientens tillstånd och slutligen beskrivs arbetsmiljö samt rutiner och samarbete i kategorin omgivning. Slutsatser: Resultatet visar att bedömning och observation av patientens andningsfrekvens påverkas av omgivning, patientens hälsotillstånd och teamarbetet mellan yrkeskategorier. Resultatet visar även på nyttan av införandet av bedömningsinstrumentet NEWS2

Frivillig Fri Fysisk aktivitet : En undersökning om bestämningsfaktorer som samvarierar med fysisk aktivitet erbjuden via arbetsgivaren

Syfte och frågeställningar Syftet med studien var att undersöka vilka faktorer som samvarierar med utnyttjandet av friskvård på arbetsplatsen för att på så sätt få en djupare förståelse för vad som kännetecknar individer som är fysiskt aktiva eller inaktiva. Frågeställningarna var: Vilka är de främsta motivationsfaktorerna till att vara fysiskt aktiv? a) bland dem som utnyttjar friskvård, b) bland dem som inte utnyttjar friskvård men är fysiskt aktiva. Vilka är det vanligaste hindren till att inte utnyttja friskvård i form av fysisk aktivitet? Vilka olika beteendemässiga och sociala faktorer samvarierar med utnyttjandet av friskvård? Metod Undersökningen var en tvärsnittsstudie som genomfördes med hjälp av en web-enkät som mestadels bestod av strukturerade svarsalternativ. Urvalet bestod av 272 anställda inom administration och service. Bearbetningen av resultatet har gjorts i statistikprogrammet SPSS där signifikansnivån sattes till (p<0,05). Tolkningen av resultatet har gjorts med utgångspunkt från Social Cognitive Theory och Self Determination Theory. Resultat De som utnyttjade friskvårdserbjudandena motiverades främst av att ”hålla sig i form och må bra” vilket enligt teorin är ett yttre motiv. De som inte utnyttjade friskvårdserbjudandena men var fysiskt aktiva motiverades främst av att de ”tycker det är kul” vilket tolkas som ett inre motiv. Det mest förekomna hindret för att inte vara fysiskt aktiv var ”jag hinner inte på grund av familjesituationen”. Resultatet visade en statistiskt signifikant samvariation mellan utnyttjande och ålder, kön, fysiskt aktiva vänner och måttet på självtillit/självförmåga. Slutsats Denna studie visar, liksom tidigare forskning antytt, att det finns ett samband mellan beteendemässiga och sociala faktorer och fysisk aktivitet. Personer som var fysiskt aktiva genom friskvård hade en högre självtillit/självförmåga än de som inte deltog, de uppgav också att de hade vänner som var fysiskt aktiva vilket antyder att det sociala stödet fungerar som en motiverande faktor men även utgör ett hinder när det saknas. Det är viktigt att sträva efter att individer styrs av inre motiv samt uppnår en hög självtillit/självförmåga som kan bidra till att man lättare klarar av de hinder som kan uppstå. Sett ur ett ledarskaps- och hälsopedagogs-perspektiv kan dessa kunskaper vara till hjälp i samband med friskvårdssatsningar på arbetsplatsen samt vid arbete med beteendeförändringar för fysisk aktivitet.Aim The purpose of this study was to investigate factors that covary with the use of wellness in the workplace in order to gain a deeper understanding of the characteristics of individuals who are physically active or inactive. Questions were: What are the main factors of motivation to be physically active? a) among users of the wellness benefit, b) among those who do not use the wellness benefit but are physically active. What are the most common barriers for not using health care in the form of physical activity? What are the various behavioural and social factors that correlated with the utilization of the wellness benefit? Method The study was a cross-sectional study conducted using a web survey that consisted mostly of structured answers. The sample consisted of 272 employees in administration and service positions. The results were processed using the statistical program SPSS where the significance level was set at (p <0.05). The interpretation of the results was based on Social Cognitive Theory and Self-Determination Theory. Results Those who used wellness benefits were primarily motivated by "keeping in shape and feel good" which in theory is an external motive. Those who did not utilize wellness benefits but were physically active were primarily motivated by the fact that they "think it's fun" which is interpreted as a single motif. The most common reason given for not being physically active was "I do not have time due to family situation". The results showed a statistically significant correlation between use and age, gender, physically active friends, and active friends, and the measure of self-efficacy. Conclusions This study indicated that there is a correlation between the behavioural and social factors and physical activity. People who were physically active through fitness had a higher self-efficacy than those who did not participate; they also reported that they had friends who were physically active, suggesting that social support acts not only as a motivating factor but also an obstacle when it is missing. It is important to seek that individuals are guided by an inner motivation and that they reach a high level of self-efficacy that can help them coop with the obstacles that may arise. From a leadership perspective these knowledge can be helpful in the context of wellness initiatives in the workplace and when working with behaviour change for physical activity